The invention relates to an open-end spinning machine with a plurality of spinning units and with at least one servicing device which can be associated with the individual spinning units, this servicing device being equipped with means for uncovering a spinning rotor disposed in a housing and with means for cleaning this spinning rotor, wherein the means for cleaning comprise a combined blower and suction device movable toward the spinning rotor, this device blowing compressed air into the spinning rotor and removing fiber residues and the like from the spinning rotor.
Even though the fiber material is cleaned by special measures on its way between the feed point and the spinning rotor of an open-end spinning unit, it is unavoidable that impurities pass into the spinning rotor which lead to soiling during the course of time. Such contaminations are the cause for an impairment of the quality of the thus-produced yarns with the passage of time. In particular, there is the danger of periodically occurring flaws in the yarn which in the hosiery product or fabric manufactured therefrom manifest themselves even more unpleasantly than in case of a ring yarn. Therefore, it is necessary under practical conditions to clean the open-end spinning rotor from time to time.
In a conventional type of construction (DOS 1,760,560) the spinning rotors are cleaned when the spinning operation has been interrupted due to a disturbance. The cleaning step is to be performed with the spinning unit in the closed condition, by slowing down or arresting the spinning rotor, so that the centrifugal forces effective on the fibers and on the impurities of the spinning rotor are reduced to such an extent that the fibers and impurities can be removed by suction via a vacuum connection joined to a housing surrounding the spinning rotor. In this procedure, the vacuum which is required anyway for normal operation is utilized, which takes care during operation of transporting the fibers to the spinning rotors. In this type of structure, difficulties are encountered with respect to adapting the vacuum both for cleaning purposes and for the operating condition. For the latter, a relatively minor vacuum is sufficient, by means of which the fibers are transported to a sliding surface of the spinning rotors. Too high a vacuum during operation is disadvantageous, since then the danger is encountered that fibers are entrained by the air flowing out of the spinning rotors which represents a loss. However, on the other hand, a relatively minor vacuum is incapable of performing an adequate cleaning action since, in part, the dirt particles adhere to the spinning rotors. Even a very high vacuum is insufficient in many cases.
In another conventional type of construction (DOS 1,560,301), pneumatic or mechanical cleaning means are introduced, with the spinning unit being closed, into the spinning rotor via an additional cleaning duct. In order to remove the dirt particles detached by this cleaning means, the speed of the spinning rotor is reduced during the cleaning step so that the suction draft necessary for the operation can then remove the dirt particles. This type of structure likewise exhibits the aforementioned disadvantages regarding the dimensioning of the vacuum. Additionally, the expense for this type of apparatus is relatively high since the cleaning means must be provided at each spinning unit. Besides, there is furthermore the danger that secondary air enters via the cleaning ducts provided for the cleaning means, interferring with the spinning operation.
In another known type of apparatus (DOS 2,008,142), the spinning rotors are cleaned by a servicing device moving along the open-end spinning machine and cleaning, in case of a thread breakage, the respective spinning rotor before the piecing step is conducted, for the purpose of removing so-called residual fibers therefrom. To this end, the servicing device is equipped with means which uncover the spinning rotor to be cleaned so that a combined blower and suction device can be applied to the rotor which enters the latter. The combined blower and suction device consists of a twin tube blowing compressed air via the outer ring into the spinning rotor; this compressed air is to be exhausted via the central tube together with the detached impurities. The twin tube penetrates into the spinning rotor. In this type of construction, the vacuum necessary for the conveyance of the fibers to the spinning rotor is produced by the spinning rotor proper which, for this purpose, is provided with ventilating bores. There is no vacuum connection arranged at the housing, so that a suction removal of the impurities by way of vacuum connections present at each spinning station is impossible.
The invention is based on the problem of providing an open-end spinning machine of the type mentioned in the foregoing wherein a perfect cleaning operation is made possible without interference in the spinning procedure. The invention resides, at least in part, in that the suction portion of the combined blower and suction device comprises a flange which, during cleaning, contacts in the manner of a lid the housing surrounding the spinning rotor and is connected to a vacuum source, and connects the housing to the suction portion.
Since the suction removal of the fibers and impurities is taken over by the servicing device, the vacuum necessary for the operating condition can be designed exactly for the tasks to be accomplished thereby, without there being the danger that due to increased vacuum fibers are sucked out of the spinning rotor in the operating condition, and this results in a marked reduction in fiber losses and also decreases the danger of contamination by fly. The invention starts with the realization that, in spite of the vacuum connections present at each spinning unit, it is more expedient to equip the servicing device with a suction removal possibility since in such a case the cleaning step can likewise be controlled more satisfactorily. In this connection, the present invention attains the advantage that the spinning rotor is freed from fiber residues and impurities not only on its inside but also on its outside so that any fibers adhering perhaps in vent bores or the like are also safely removed as well. In this construction, it is furthermore unnecessary to decelerate the spinning rotor for the cleaning step, thus avoiding any wear and tear phenomena at any of the parts of the spinning unit during the conductance of the cleaning operation.
In a further development of the invention, the provision is made to equip the combined blower and suction device with a cover element which, when associated with the spinning rotor to be cleaned, is placed in front of an opening of the housing, by way of which the housing is connected to the vacuum source for spinning operations. Thereby, the advantage is obtained that even during cleaning, fibers cannot enter the conduit which takes care of the vacuum required for the operation. Besides, there is the advantage that the preferably substantially higher vacuum during the cleaning step cannot exert any influence on the vacuum of the adjacent spinning units which are still in operation.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.